JPS627772A - Ink for ink jet recording - Google Patents

Abstract

PURPOSE:The titled ink having improved signal response properties, extrusion stability, light resistance, weather resistance, water resistance, etc., using an aqueous solvent and a trisazo compound having a specific structure as dye. CONSTITUTION:The titled ink containing water or a mixture of water and a water-soluble organic solvent as a solvent and preferably 0.5-20wt% compound(preferably C.I. Direct Black 154 shown by the formula II) shown by the formula I(Z1 and Z2 are unsubstituted or 1-2C alkyl; R3 and R4 are 1-2C alkyl) as a dye. A polyhydric alcohol or a polyhydric alcohol lower alkyl ether is preferable as the aqueous organic solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ink used for inkjet recording.

(Prior Art) Ink used for inkjet recording is mainly formed from a solvent and a dye, and the characteristics of the ink itself are influenced by the characteristics of the dye itself contained.

In particular, the characteristics required for a recording liquid, so-called signal response, stability of droplet formation, stability of ejection amount and speed.
Intermittent recording stability, recording storage stability, fixability to the recording material, light fastness of recorded images, weather resistance, water resistance, etc. vary greatly depending on the characteristics of the dye.

(Problems to be solved by the invention) The ink used in conventional inkjet recording is
These dyes do not fully satisfy the above-mentioned recording characteristics; rather, they may cause clogging at the ink ejection ports (orifices) and variations in fixing accuracy depending on the type of recording material, resulting in the inability to obtain clear images. It was difficult to provide.

(Means for Solving the Problems) Therefore, the present invention was devised to solve the above problems, and uses water or a mixture of water and a water-soluble organic solvent as the solvent, and dyes with the structural formula of By using the shown ink, an inkjet recording ink having excellent recording characteristics such as recording response and ejection stability, storage stability, and fixability to a recording material is provided.

In the above structural formula, C, Z2 represents an unsubstituted alkyl group or an amino group having 1 or 2 carbon atoms, and R3
, R4 represents an alkyl group having 1 or 2 carbon atoms.

(Example) Hereinafter, the inkjet recording ink (hereinafter referred to as ink) of the present invention will be described in detail based on specific examples.

The solvent mainly consists of water or a mixture of water and a water-soluble organic solvent. Examples of water-soluble organic solvents include alkyl alcohols having 1 to 4 carbon atoms, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, 5ea-butyl alcohol, tert-butyl alcohol, and isobutyl alcohol; Amides such as dimethylformamide and dimethylacetamide.

Ketones or keto alcohols such as acetone and diacetone alcohol, ethers such as tetrahydrofuran and dioxane, and polyethylene glycol.

Polyalkylene glycols such as polypropylene glycol, ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1.2
．． 6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol and other alkylene glycols containing 2 to 6 carbon atoms; glycerin; ethylene glycol methyl ether; diethylene glycol methyl (or ethyl) ether; Lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether are used.

In particular, polyhydric alcohols such as diethylene glycol and triethylene glycol monomethyl (or ethyl)
Lower alkyl ethers in polyhydric alcohols such as ethers.

It is preferable as a solvent for the dye represented by. The ratio of the water-soluble organic solvent to the total weight of the ink is 5 to 95.
Weight percentages, particularly preferably in the range from 2° to 50 weight percent, are suitable.

The amount of water is determined depending on the type of water-soluble organic solvent and the characteristics required of the ink, but it is usually in the range of 1 to 90% by weight, particularly preferably in the range of 20 to 70% by weight.

On the other hand, to explain the structure of the dye in more detail, in the structural formula, Z+ and Z2 are each unsubstituted or an alkyl group having 1 or 2 carbon atoms (CnHin++).
A + or substituted amine group (Nl2) is preferred, and R3 and Ra are each an alkyl group (CnH2n++) having 1 or 2 carbon atoms, preferably a methyl group (CH
3).

That is, C, which has the structure of the following formula, 1. Direct black 154.

This C. I. The content of Direct Black 154 is determined depending on the type of water-soluble organic solvent constituting the solvent and the properties required for the ink, but it is usually 0.0% based on the total weight.
A range of 5 to 20 weight percent is suitable, more preferably a range of 1 to 10 weight percent.

In addition, in order to balance recording characteristics, storage stability, fixability to recording materials, etc., viscosity modifiers (polyvinyl alcohol, cellulose, water-soluble resins, etc.) and surfactants (cations, anions, or nonionic), surface tension modifiers (jetanolamine, triethanolamine, etc.)
, a pH adjuster using a buffer solution, etc. may be added as appropriate.

Next, the composition of the ink of the present invention will be explained using specific examples.

Example-1 The above C. I. An inkjet recording ink was formed using Direct Black 154 with the following composition ratio.

C. I. Direct Black 154...5 parts by weight Ion exchange water...50 parts by weight Diethylene glycol...44 parts by weight Urea
...1 part by weight Each of the above compositions was thoroughly mixed and dissolved individually in a container, and filtered through a Teflon filter (
An ink was obtained by passing through a pressurized gun with a pore size of 1 l and then aeration (vacuum pump).

This ink was applied to an on-demand recording head (discharge orifice diameter 50IL, piezo vibrator drive power 8Qv, frequency 4
The data were recorded using a recording device having a frequency of kHz (KHz).

All exhibited good characteristics, and the following evaluations of 1 to 2 were obtained as recording results.

■Long-term shelf life of the ink Even after the ink was sealed in a glass container and stored at -30"0 and 70℃ for 6 months, no precipitation of insoluble matter was observed, and there was no change in the physical properties or color tone of the ink, which is extremely good. It showed excellent storage stability.

(2) Ejection Stability Continuous ejection was carried out for 24 hours in an atmosphere at room temperature of 40°C and 50°C, and in both cases, the ejection amount and speed were stable and high-quality recording was performed.

(2) Ejection response In both the intermittent ejection every 2 seconds and the ejection after being left for 3 months, no clogging occurred at the orifice tip, and stability and uniformity suitable for continuous intermittent recording were obtained.

(Fixability to Recording Materials) After recording on the recording materials shown in the table below, the recorded area was rubbed with a finger after 15 seconds had elapsed and the presence or absence of image rubbing or blurring was determined. There was no image rubbing, blurring, etc. on any of the recording materials, and it was demonstrated that the fixing properties allow recording without limiting the type of recording material.

Recording material Product name Classification Manufacturer Silver ring
High-quality paper Sanyo Kokusaku Pulp ■Seven Star
〃 Hokuetsu Paper − Shiropeony Medium-quality paper
Honshu Paper ■IJ Paper (M) Inkjet Paper Mitsubishi Paper ■ ■Quality of Recorded Image The image was high in density and clear, and the rate of decrease in density was within 1% after being exposed to room light for 3 months. In addition, there was very little image bleeding after immersion in water for 1 minute, and overall image quality was excellent in terms of water resistance, weather resistance, abrasion resistance, etc.

Comparative Example C having the structure of the following formula: 1. An inkjet recording ink was formed using Direct Black 18, and the same study as in Example 1 was conducted.

C. I. Direct Black 19...5 parts by weight Ion-exchanged water...50 parts by weight Diethylene glycol...44 parts by weight Urea
...The results of examining 1 part by weight were as follows.

■Long-term storage - Precipitation of insoluble matter began during the second month of storage at 30°C and 70°C.

■Discharge stability Discharge was unstable and images were often distorted.

■Discharge response Clogging occurred at the tip of the orifice, resulting in many uneven recordings.

(2) Fixability of Recording Material When rubbed with a finger 15 seconds after recording, the image was rubbed and smeared.

- After one month of exposure to indoor light, the density decreased by 10%, and when immersed in water, the image blurred significantly.

(Effects of the Invention) As described above, the inkjet recording ink of the present invention uses water or a mixture of water and a water-soluble organic solvent as the solvent and the dye has the above-mentioned structural formula. It has excellent recording properties such as droplet formation stability, ejection stability, and continuous intermittent recording stability, and also has excellent storage stability of recorded images such as light resistance, weather resistance, and water resistance, and also has excellent fixation versatility on recording materials. Also excellent,
Compared to conventional inks, this ink exhibits the ink characteristics necessary for inkjet recording.

Claims (4)

[Claims] (1) In inkjet recording ink formed by containing a dye in a solvent, the solvent is water or a mixture of water and a water-soluble organic solvent, and the dye is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ An inkjet recording ink featuring: (2) The above dye has a structural formula of C. I. The inkjet recording ink according to claim 1, which is Direct Black 154. (3) The inkjet recording ink according to claim 1, wherein the water-soluble organic solvent is a polyhydric alcohol or a lower alkyl ether of a polyhydric alcohol. (4) Said C. I. Direct black 154 is 0.
The inkjet recording ink according to claim 1, characterized in that the content is 5 to 20 weight percent.